AMPK is a serine-threonine kinase, which is activated by AMP, and has three subunits, α, β and γ. In each subunit, there exist multiple isoforms (α1, α2, β1, β2, γ1, γ2 and γ3).
AMPK is involved in various physiological functions, such as suppression of gluconeogenesis and inhibition of fatty acid synthesis in liver and incorporation of sugars and an increase in fatty acid oxidation in skeletal muscles, as an energy sensor in living organisms, and has attracted attention as a target molecule of a therapeutic agent for diabetes. Therefore, an AMPK activator is expected to be effective in the treatment of diabetes as an insulin resistance improving drug, which has an insulin independent hypoglycemic effect and a lipid improving effect (Non-Patent Document 1).
Patent Documents 1 to 8 disclose a variety of compounds having an AMPK activating effect. However, an indole derivative like the compound of the present invention is not disclosed in any of the documents.
Patent Document 9 describes the derivatives substituted with —C(═O)— group at the 2-position of indole as compounds useful for a remedy for benign prostatic hyperplasia.
Patent Document 10 describes the following compounds as compounds useful for the treatment of hepatitis C.

Patent Document 11 describes the derivatives substituted with —C(═O)NH— group at the 2-position of indole as compounds useful for the treatment of HIV.
Patent Document 12 describes the derivatives substituted with —C(═O)— group at the 2-position of indole as compounds useful for the treatment of psychosis.
Patent Document 13 describes the derivatives substituted with —C(═O)NH— group at the 2-position of indole as compounds useful for the treatment of obesity or atherosclerosis.
Patent Document 14 describes the following compound as a compound useful for ultraviolet absorbers.

Patent Document 15 describes the following compound as a compound useful for the treatment of hypertension.

Patent Document 16 describes the following compounds as compounds useful for the chromogenic substrates of sialidases.

Patent Document 17 describes the following compound as compounds useful for agrochemicals.

Patent Document 18 describes the following compound as a compound useful for insecticides.

Patent Document 19 describes the following compound as a compound useful for organic semiconductor materials.

Patent Document 20 describes the following compounds as compounds useful for the treatment of cancer.

Patent Document 21 describes the following compound as compounds useful for herbicides.

Patent Document 22 describes the following compound as compounds useful for ultraviolet absorbers.

However, any of Patent Documents 9 to 22 does not disclose the AMPK activating effect.
Non-patent Document 2 describes the derivatives substituted with —C(═O)— group at the 2-position of indole as compounds useful for the treatment of rheumatoid arthritis.
Non-patent Document 3 describes the derivatives substituted with —C(═O)— group at the 2-position of indole as compounds useful for the treatment of HIV.
Non-patent Document 4 describes the derivatives substituted with —C(═O)NH— group at the 2-position of indole as compounds useful for the treatment of cardiovascular disease.
Non-patent Documents 5 to 9 disclose the derivatives substituted with —C(═O)— group at the 2-position of indole.
Non-patent Document 10 describes the derivatives substituted with —C(═O)— group at the 2-position of indole as compounds useful for the treatment of insomnia.
Non-patent Document 11 describes the derivatives substituted with ethoxy group at the 2-position of indole and chloro group at the 5-position of indole.
Non-patent Document 12 describes the derivatives substituted with isopropyl group at the 2-position of indole and —S—CH3 group at the 3-position of indole.
Non-patent Document 13 describes the following compounds.

However, any of Non-patent Documents 2 to 13 does not disclose the AMPK activating effect.
The following compounds are hit by searching structures on SciFinder (online database), but there is no literature information and the AMPK activating effect of the compounds is not described.
